A study has been made of the luminescence during He- or Ar-ion bombardment to Tb-implanted Al 2O 3. Tb-ions of 100 keV were implanted in colorless and transparent single crystal α-Al 2O 3 at a dose of 5 × 10 15 Tb/cm 2 nearly at room temperature. The implanted specimens were annealed in a nitrogen gas atmosphere at 800 for 1 h. The luminescence spectra were measured during 100 keV-Ar or 50 keV-He bombardment of the specimens using a spectrometer with three optical filters and a photomultiplier. The beam current densities ranged from 0.01 to 0.1 μA/cm 2. The spectra emitted by Ar bombardment of Tb-implanted specimens are almost the same as those by He bombardment, except for the peaks corresponding to defects in the sapphire itself. The luminescence has four clear peaks identified as emission due to D-F transitions of the Tb 3+ state, and its color is green due to the strongest peak at 550 nm. Annealing results in the increase of luminescence. He bombardment causes the peaks to be stronger than Ar bombardment. The peak intensity of luminescence rises in proportion as the He-ion beam current density increases. From the results, it is concluded that ion beam induced luminescence of Tb-implanted Al 2O 3 becomes stronger by annealing and He bombardment with a high current.